New live mycobacterial vaccines: the Geneva consensus on essential steps towards clinical development.

As the disease caused by Mycobacterium tuberculosis continues to be a burden, which the world continues to suffer, there is a concerted effort to find new vaccines to combat this problem. Of the various vaccines strategies, one viable option is the development of live mycobacterial vaccines. A meeting with researchers, regulatory bodies, vaccines developers and manufactures was held to consider the challenges and progress, which has been achieved with live mycobacterial vaccines (either modified BCG or attenuated M. tuberculosis). Discussion led to the production of a consensus document of the proposed entry criteria for Phase I clinical trials of candidate live mycobacterial vaccines. The vaccine must be characterised thoroughly to prove identity and consistency, as clinical trial lots are prepared. In pre-clinical studies, greater protective efficacy as well as improved safety potential relative to BCG should be considered when assessing potential vaccine candidates. A standard way to measure the protective efficacy to facilitate comparison between vaccine candidates was suggested. Additional safety criteria and verification of attenuation must be considered for attenuated M. tuberculosis. Two non-reverting independent mutations are recommended for such vaccines. When entering Phase I trials, enrollment should be based upon an acceptable characterisation of the study population regarding mycobacterium status and exclude HIV(+) individuals. BCG could be used as a comparator for blinding during the trials and to properly assess vaccine-specific adverse reactions, while assays are being developed to assess immunogenicity of vaccines. The proposed criteria suggested in this consensus document may facilitate the movement of the most promising vaccine candidates to the clinic and towards control of tuberculosis.

Advancing TB vaccines to Phase I clinical trials in the US: regulatory/manufacturing/licensing issues.

This article discusses the steps required to file an investigational new drug (IND) application to the United States Food and Drug Administration (FDA) and begin a Phase I trial of a new tuberculosis vaccine in the US. Many different groups play a role in bringing a new vaccine to market. But it is the researcher who begins the process by converting an idea into a new vaccine construct. Awareness of certain chemistry, manufacturing, and control (CMC) issues on the part of the researcher who develops the investigational vaccine can prevent later problems that might cause the vaccine to be unapprovable or fail to meet regulatory requirements for eventual licensure. CMC information included in an IND is described.

A novel approach to develop anti-HIV drugs: adapting non-nucleoside anticancer chemotherapeutics.

Some anticancer drugs, but not all, inhibit replication of human immunodeficiency virus (HIV) and thus, exhibit a therapeutic potential. Such drugs, unlike the traditional HIV enzyme inhibitors, could suppress HIV strains that are resistant to inhibitors of viral enzymes, decrease proviral burden in vivo, or reduce reservoirs of infection via killing infected cells. Thus, they may be an effective adjunct therapy or perhaps result in a cure. The incidence of HIV infection and AIDS mortalities continue to increase worldwide, including the United States and parts of Africa, with a parallel increase in a number of other manifestations, including AIDS defining malignancies. The basis for continual spread of HIV presumably in large part stems from the viral resistance to previously successful drugs and the lack of curative antiretroviral drugs. To reverse these trends, other approaches for AIDS therapy must be developed. One possibility is the development of potent anticancer drugs, that exhibit anti-HIV activities. At least four chemically and pharmacologically distinct classes of anticancer drugs, i.e. certain cyclin-dependent kinase inhibitors (CDKIs), topoisomerase 1 enzyme (top 1) inhibitors, non-nucleoside antimetabolites, and estrogen receptor ligands are promising candidates. These drugs, at high doses are used for cancer therapy; at lower concentrations they exhibit anti-HIV activities in cultured cells. While the antiretroviral and the anticancer activities of the cdk inhibitor flavopiridol appear to be mutually exclusive and unrelated in cells and animal model(s) of HIV disease, the top 1 inhibitor 9-nitrocamptothecin, as well as the cdk-inhibitor roscovitine inhibit replication of HIV via selective sensitization of HIV-infected cells to apoptosis. In contrast, the inhibitory effects of these compounds are different from other cancer therapeutics that, at toxic concentrations, activate HIV either in cultured cells (such as certain ingenol and butyrate derivatives) and/or in patients (such as the widely used cyclophosmamide and cisplatin). This quality may lead to the eradication of proviral reservoirs, which is not accomplished by the currently available antiretroviral drugs. In this review, relevant available clinical and in vitro data that either support or discourage using certain anticancer drugs for treatment of HIV disease, and the rationales for developing novel antiretroviral drugs that may target infected cells rather than viral proteins are discussed.